IRG 24
also Schott IRG 24
IRG 24 is a Schott infrared optical glass formulated to extend transmission into the near- and mid-infrared for thermal imaging and IR sensing.
Reference datasheet — IRG 24 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the CHG condition
IRG 24 tempers and conditions
IRG 24 is supplied in 2 conditions, soft to hard. CHG is the default FabDigit quotes; the values on this page are for it.
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
CHGDefault Chalcogenide As₄₀Se₆₀ glass | Pick for 3–5 µm and 8–12 µm thermal imaging optics that must be diamond-turned or precision-moulded at low temperature. | 16 | 0 | 110 HV | 0.2 W/m·K | |
Germanate (GeO₂-based) IR transmitting glass | Pick when visible-to-~5 µm transmission plus hard, polishable, high-temperature-capable oxide glass is needed (windows, domes, MWIR lenses). | 45 | 0 | 460 HV | 0.9 W/m·K |
What is IRG 24?
IRG 24 is a Schott infrared optical glass formulated to extend transmission into the near- and mid-infrared for thermal imaging and IR sensing. It is chosen because its low glass transition temperature (Tg ≈ 185 °C) suits precision glass moulding and single-point diamond turning, so aspheres and diffractive surfaces can be produced without post-polishing. Density is 4.64 g/cm³, elastic modulus 18.3 GPa, tensile strength 16 MPa with 0% elongation and thermal conductivity 0.2 W/m·K, with service capped at 120 °C. The bare surface is soft and slowly tarnishes in humid air, so coating is mandatory. IRG 24 has a density of 4.64 g/cm³ (0.168 lb/in³), heavier than 81% of glass grades. IRG 24 has a tensile strength of 16 MPa (2.32 ksi), weaker than 91% of glass grades. Elongation at break is 0% and the elastic modulus is 18.3 GPa (2.65 Msi).
What is IRG 24 used for?
- thermal imaging lenses
- IR sensor windows
- night-vision optics
- laser rangefinder optics
Advantages
- Easy to machine — 85/100, better than 100% of glass grades
Limitations
- Poor heat conductor — 0.2 W/m·K (0.116 BTU/hr·ft·°F), worse than 100% of glass grades
- Low stiffness — 18.3 GPa (2.65 Msi), worse than 95% of glass grades
- Low fracture toughness — 0.17 MPa·√m (0.155 ksi·√in), worse than 93% of glass grades
- Limited service temperature — 120°C (248 °F), worse than 93% of glass grades
- Heavy — 4.64 g/cm³ (0.168 lb/in³), worse than 81% of glass grades
IRG 24 properties
Typical room-temperature values for IRG 24-CHG; bars are the position among glass grades.
Physical4
IRG 24 has a density of 4.64 g/cm³ (0.168 lb/in³), heavier than 81% of glass grades.
Mechanical12
IRG 24 has a tensile strength of 16 MPa (2.32 ksi), weaker than 91% of glass grades. Elongation at break is 0% and the elastic modulus is 18.3 GPa (2.65 Msi).
Thermal5
IRG 24 is rated for continuous service to 120°C (248 °F). It conducts heat at 0.2 W/m·K (0.116 BTU/hr·ft·°F), worse than 100% of glass grades. Thermal expansion is 20.7 µm/m·K (11.5 µin/in·°F).
Electrical3
IRG 24 has an electrical resistivity of 1×10¹¹ Ω·m.
Chemical & Environmental2
Corrosion resistance is good (55/100), worse than 74% of glass grades.
Manufacturability2
IRG 24's machinability is excellent (85/100, better than 100% of glass grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the glass family
Yield strength against density for every glass grade FabDigit runs. IRG 24 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with IRG 24
Is IRG 24 easy to machine?
Excellent single-point diamond turning (low Tg, no crystalline structure); grind/polish with light pressure and non-alkaline slurries to avoid surface staining.
Can IRG 24 be welded?
Not weldable; parts are joined by optical contacting, epoxy bonding or metal-mount cementing, and glass is fused only during melt/casting under vacuum.
Can IRG 24 be formed, bent or molded?
Precision glass moulding near Tg ≈ 185 °C in inert atmosphere gives aspheres and diffractive surfaces without post-polishing; anneal slowly to avoid stress birefringence.
IRG 24 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Se≈60 at% Se (As₄₀Se₆₀ base glass) | 58 – 63 | 61.3 |
| As≈40 at% As; melted in sealed silica ampoule from 5N-6N elements | ≥ 37 (balance) |
What surface finishes work on IRG 24?
Always AR-coat (DLC or ZnS/YF₃ stacks) — the bare surface is soft, scratch-prone and slowly tarnishes in humid air.
Equivalent designations
Standards and trade names that resolve to IRG 24 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Trade names
- Schott IRG 24
- Also called
- Infrared Transmitting Glass
How much does IRG 24 cost?
IRG 24 is a high-cost glass ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
IRG 24 — frequently asked
What is IRG 24 used for?
IRG 24 is typically used for thermal imaging lenses, IR sensor windows, night-vision optics and laser rangefinder optics. In short: diamond-turnable IR glass; mouldable near 185 °C; near/mid-IR transmission.
What is the tensile strength of IRG 24?
IRG 24 has a typical tensile strength of 16 MPa (2.32 ksi) — weaker than 91% of glass grades. Strength varies by condition: see the 2 listed tempers.
Is IRG 24 easy to machine?
Yes — machinability is rated excellent (85/100, better than 100% of glass grades). Excellent single-point diamond turning (low Tg, no crystalline structure); grind/polish with light pressure and non-alkaline slurries to avoid surface staining.
Can IRG 24 be welded?
Not weldable; parts are joined by optical contacting, epoxy bonding or metal-mount cementing, and glass is fused only during melt/casting under vacuum.
What surface finishes work on IRG 24?
Always AR-coat (DLC or ZnS/YF₃ stacks) — the bare surface is soft, scratch-prone and slowly tarnishes in humid air.
Can IRG 24 be formed, bent or molded?
Precision glass moulding near Tg ≈ 185 °C in inert atmosphere gives aspheres and diffractive surfaces without post-polishing; anneal slowly to avoid stress birefringence.
What is the maximum service temperature of IRG 24?
IRG 24 is rated for continuous use to about 120°C (248 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does IRG 24 cost?
IRG 24 is a high-cost glass ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- Infrared Chalcogenide Glasses IRG 22–IRG 27 — SCHOTT AG (2023)
- Infrared Transmitting Glasses IRG 2 / IRG 11 (germanate and calcium-aluminate types) — SCHOTT AG (2022)
- AMTIR-2 (As₄₀Se₆₀) optical and mechanical data — Amorphous Materials Inc. (2021)
- Handbook of Optics, Vol. IV — Properties of Infrared Optical Materials — OSA/McGraw-Hill (2010)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.